The present invention relates to toothbrushes in general and more specifically to a toothbrush bristle configuration providing improved and effective removal of microbial plaque accumulation from the exposed and subgingival surfaces of teeth.
Plaque control retards the formation of calculus and is critical in the prevention of periodontal disease.
In the past, the most dependable mode of controlling plaque has been mechanical cleansing with a toothbrush and other cleansing aids. However, conventional toothbrushes have not been entirely effective in removing the microbial plaque from beneath the gingival margin in the sulcus and the high plaque retaining areas in the interproximal embrasures of adjacent teeth. This is due to several reasons. First, a straight tip of a conventional brush bristle does not tend to enter the gingival sulci when the brush is held in a plane generally perpendicular to the long axis of the tooth. Secondly, the sharp point of the bristle tends to damage the gingiva and mucosa if the brush is held at an acute angle to the long axis of the tooth in an attempt to enter the sulci. Thirdly, the flex of the bristles tends to prevent the most effective bristle tip posture for cleansing when the brush is activated.
Studies show that the most aggressive mechanical cleansing should be directed toward the tooth surface, much less so toward the gingival surface and none toward the base of the gingival sulcus. The basis for these observations is as follows.
The development of gingival inflammation and dental cavities is most frequently caused by failure to remove dental plaque from the subgingival surface of the tooth and to a much lesser extent materia alba from the gingival surface in the subgingival space. Both dental plaque and materia alba can form within several hours and therefore frequent mechanical cleansing is essential. Materia alba which consists primarily of an acquired bacterial coating and desquamated epithelial cells, leucocytes and a mixture of salivary proteins and lipids is a soft sticky deposit less adherent than dental plaque. It can be flushed away with a water spray but more completely removed from the gingiva with mild mechanical cleansing.
Dental plaque is formed by oral microorganisms which synthesize harmful products which are destructive to the tooth and gum when not removed from the gingival sulcus. The toxins formed by the microorganisms cause cellular damage to the gingiva with subsequent inflammation (gingivitis) and eventually destruction of the supporting structures (periodontitis). When gingivitis occurs, vascular dilatation, capillary proliferation, engorged vessels and sluggish venous return causes a stretched and thinned epithelium that is sensitive to mechanical trauma such as aggressive brushing.
Dental plaque with associated gingivitis also causes exposure of the root surface (recession) with increased occurrence of cavities (dental caries). Exposure of the root surface can also occur due to faulty brushing by repeated direct trauma to the base of the sulcus (gingival abrasion). When a pathologically deepened gingival sulcus (periodontal pocket) occurs, the pathological condition may become exacerbated because plaque can more readily occur. If dental plaque is not removed calculus is formed by mineralization of the bacterial plaque. Calculus can form within several hours of plaque formation. Calculus has a bacterial plaque coating and exacerbates gingivitis and gingival recession by both chemical irritation from the formed toxins and destruction from the mechanical irritation of the calculus mass. Subgingival calculus usually extends near but does not reach the base of periodontal pockets in chronic periodontal lesions. Calculus holds the plaque against the gingiva.
Since materia alba can be removed by light mechanical cleansing and gingival inflammation causes thinning of the gingival epithelium the mechanical cleansing requirement of the gingival surface is much less than the requirement for removing dental plaque from the surface of the teeth. Accordingly, a toothbrush which fulfills these requirements while protecting the base of the gingival sulcus is desirable.
The surfaces of teeth in a set of teeth are typically non-uniform and curved with the curved surfaces varying in magnitude and direction from tooth to tooth. Heretofor, the bristle support of a conventional toothbrush has been typically rigidly mounted to the end of the toothbrush handle. Typically the length and width of a conventional bristle support exceeds the distance between two adjacent teeth so that frequently the surfaces of the teeth in the interproximal embrasures are not contacted by the bristles of the bristle support, particularly if the bristles are relatively stiff.
Another disadvantage of prior known toothbrushes is that the cleansing of the subgingival surfaces of the teeth is difficult to do by the "up and down" mechanical motion typically accompanying a conventional toothbrushing technique. This is because the sulcus is relatively shallow and it is difficult for one brushing one's teeth to judge how deeply to penetrate the sulcus without causing injury to the base of the sulcus. Consequently, there is a tendency to avoid penetrating the sulcus.
Because the teeth and gingiva have poor sensory perception, the user of a toothbrush must rely on the brush design to assure proper position and pressure of the cleansing elements against the teeth surfaces. The maximum cleansing element contact is assured by designing maximum flexibility into the brush parts while retaining the brush's capability to provide sufficient pressure of the cleansing tips against the teeth to remove the plaque and not damage the enamel and gingiva.
Toothbrush bristles of various configurations are disclosed in patents to Pomeroy, U.S. Pat. No. 4,167,794, Hills, U.S. Pat. No. 3,722,020, Brant, U.S. Pat. No. 3,295,156, Axelsson, U.S. Pat. No. 3,939,520, and Cooney, U.S. Pat. No. 2,088,839. Toothbrushes having moveable bristle supports of various configurations are disclosed in patents to Rashbaum, U.S. Pat. No. 3,398,421, Akizawa, U.S. Pat. No. 1,932,878, and Doolittle, U.S. Pat. No. 1,260,258.